Phytochemical Study and Antioxidant Activity of Annona muricata (Annonaceae) and Corchorus olitorius (Tiliaceae) Two Medicinal Plants from the Ivorian Pharmacopoeia Used in the Treatment of Diabetes

Annona muricata and Corchorus olitorius are two medicinal plants whose leaves are widely used in Ivory Coast both in nutrition and for the treatment of various pathologies because of their phytochemical compositions. The objective of this study was to determine the phytochemicals and to assess the antioxidant property of the leaves of these two plants. The phytochemical study was carried out using tests for the identification and quantification of phytoconstituents. As for the study of antioxidant activity, it was carried out by measuring the anti-free radical activity either by ABTS or by DPPH. Qualitative phytochemical screening revealed the presence of flavonoids, polyphenols, saponins, sterols, catechetical tannins and terpenes. The quantitative phytochemical screening of the extracts showed that the content of flavonoids (329.10 ± 2.51 mg Eq quercetin/Kg) and that of polyphenols (82.09 ± 0.13 mg Eq gallic acid/g) of Annona muricata are higher than the content of flavonoids (178.45 ± 1.09 mg Eq quercetin/Kg) and that of polyphenols (67.98 ± 5.22 mg Eq gallic acid/g) of Corchorus olitorius. The results of the antioxidant activity by measurement of the ABTS radical shows that the aqueous extract of Annona muricata exhibits the best activity with an IC50 value of 1.79 ± 0.15 μM, while the aqueous extract of Corchorus olitorius records an IC50 value of 2.64 ± 0.05 μM. Similar results are observed with the measurement of DPPH. The various metabolites demonstrated have various therapeutic properties which may be involved in the treatment of diabetes. This would confirm the therapeutic use reported by the populations. However, the evaluation of the antimalarial, antibacterial and anti-inflammatory activities as well as the toxicity test of the aqueous extract of these plants would be necessary.